The present invention relates to wide mouth blow-molded plastic containers, and more particularly, the present invention relates to such containers which are particularly suited for hot fill applications.
In the manufacture of blow molded plastic bottles for containing liquids, such as beverages, it is customary to utilize an injection-molded preform having a threaded finish which forms the threaded finish of the container blown from the preform. The preform may be injection molded from a variety of desirable plastic materials, a currently particularly preferred material being polyethylene terephythalate (PET).
In hot fill applications, i.e. applications where the blown container is filled with a liquid at a temperature in excess of 180xc2x0 F. (82xc2x0 C.), capped immediately after filling, and allowed to cool to ambient temperatures, vacuum absorption panels are generally provided in the body of the container to accommodate vacuum induced shrinkage resulting from the cooling of the container contents. In such containers, the injection molded threaded finish undergoes a minimal amount of distortion in the hot fill process. Hot fill containers molded of PET by this technique have found widespread acceptance in the marketplace.
For quite some time, there has been a need in the marketplace for a so-called wide-mouth container for hot fill applications. A wide mouth container enables the consumer to scoop-out contents which are not readily flowable. In the early 1980""s, attempts were made to produce hot fillable PET containers having wide mouths by blow molding a thread on a portion of a PET preform below the threaded finish, thereby forming an intermediate article having a threaded region with blown threads. The intermediate article had a moil portion above the blown threads. The moil portion was subsequently severed, leaving a finished wide-mouth container. This manufacturing technique and resulting containers are disclosed in U.S. Pat. Nos. 4,496,064; 4,618,515; and 4,665,682.
For reasons not fully known, these wide-mouth containers were not successful in the marketplace. There is, however, a current need for a hot fillable wide mouth container which is particularly suited for packaging viscous products, such as applesauce, and the like.
With the foregoing in mind, a primary object of the present invention is to provide a commercially satisfactory wide-mouth blow-molded plastic container which is particularly suited for viscous fluid hot fill applications.
Another object of the present invention is to provide a suitable wide mouth blown plastic container which has a blown finish that resists distortion resulting from hot fill processing.
A further object of the present invention is to provide a method of manufacturing a wide-mouth container, and a preform, which is enables commercially acceptable hot fillable wide-mouth plastic containers to be produced by means of high speed manufacturing equipment in a manner that ensures consistent quality and performance.
In the present invention, a preheated preform is disposed in a mold cavity having a particular surface configuration which enables an intermediate container article to be severed at a precise location. The moil design cooperates with the preform to ensure the accurate placement of desirably-thick crystallized material in the blown threaded finish. It also produces an inturned flange on the inside of the blown threaded finish after the moil portion of the intermediate article has been severed. The moil portion is severed by rotating the intermediate article relative to an elongate cutter as the intermediate article advances. The preform has regions of varying thickness along its wall to provide desired material thicknesses at preselected locations in the wall of the resulting container. Preform pre-heat and mold temperatures are controlled precisely for achieving the desired hot fillable container. Also, bayalage cooling is utilized in the region of the blown threaded finish to prevent material shrink-back and to achieve the desired distortion resistance.